Biomedical subjects

L Olson

Publications and source records attributed to L Olson.

At least 469 records · Page 26Linked to original sources

PubMed1975

Brain tissue transplanted to the anterior chamber of the eye: 3. Substitution of lacking central noradrenaline input by host iris sympathetic fibers in the isolated cerebral cortex developed in oculo.

Fetal parietal cerebral cortex was homologously transplanted to the anterior chambers of the eyes of adult rats. The transplants got vascularized, proliferated, as measured by in vivo stereoscopic inspections, and differentiated into brain tissue similar to cortex cerebri in situ and survived for long times, greater than 41/2 months. Fibers from the intact sympathetic adrenergic ground plexus of the iris were able to innervate the transplants in an organotypic way regarding fluorescence morphology, pattern of distribution of the nerve terminals and, to a certain extent, density of innervation, the only variable parameter being density of innervation. Thus, in unpretreated or MAO inhibited transplants only rather few to scattered terminals could be found, while after preincubation in 10(-5)M alpha-methyl-noradrenaline the number of visible terminals was normal or slightly less than normal, as compared to cortex cerebri in situ. When superior cervical ganglia (SCG) were transplanted together with fetal cortex tissue to sympathetically denervated eyes the ingrowth in the cortex tissue was similar to that after single cortex transplantation combined with 5 day old SCG, while a marked hyperinnervation was encountered when combined with adult SCG. It is concluded that the developing cortex cerebri, deprived of its normal CNS source of adrenergic nerves, is able to receive sympathetic adrenergic nerves from the iris in an organotypic way upon transplantation to the anterior chamber of the eye.

Animals↗

PubMed1975

Formation of a functional adrenergic input to intraocular cerebellar grafts: ingrowth of inhibitory sympathetic fibers.

The intraocular transplantation technique was used to study the ingrowth of peripheral sympathetic adrenergic nerves from the iris into transplants of fetal rat cerebellum, and the possible function of these nerves. The transplants, grown in oculo for one-half to eight months, were analyzed by fluorescence histochemistry and electrophysiological techniques. Peripheral sympathetic adrenergic fibers from the iris were able to grow into the cerebellar transplants and arborize in a pattern similar to that in situ, appearing in all three cortical layers and the noncortical areas of the transplants. The density of visible nerves without pretreatment and after preincubation in 10(-6) or 10(-5) M alpha-methylnorepinephrine was comparable to mature rat cerebellum. The spontaneous discharge of the Purkinje cells in oculo was inhibited by microiontophoresis of norepinephrine (NE) and amphetamine in sympathetically innervated, as well as sympathectomized transplants denervated by ganglionectomy. The NE response was blocked by the adrenergic beta-receptor blocker MJ-1999. GABA also inhibited the Purkinje cell activity while glutamate accelerated the discharge. Parenteral amphetamine inhibited Purkinje cell activity in sympathetically innervated transplants, but was ineffective in denervated transplants. The Purkinje cell spontaneous activity was inhibited by electrical stimulation of the NE fiber input through the cervical sympathetic trunk. This inhibition could be antagonized by parenteral reserpine or the beta-adrenergic antagonist propranolol. The responses of the Purkinje cells within the transplants to drugs and transmitters mimic those of the adult rat in situ. In view of the fluorescence histochemical evidence for an ingrowth of peripheral sympathetic adrenergic fibers into the cerebellar transplants, and the results of stimulating the sympathetic trunk, it is suggested that peripheral adrenergic fibers may be able to establish functional connections with the Purkinje cells similar to the cerebellar adrenergic synapses normally formed in situ by fibers from the locus coeruleus.

Amphetamine↗

PubMed1975

Brain tissue transplanted to the anterior chanber of the eye: 2. Fluorescence histochemistry of immature catecholamine- and 5-hydroxytryptamine neurons innervating the rat vas deferens.

Small pieces of the wall of the rat vas deferens were homologously transplanted to the anterior chamber of the eye together with small pieces of embryonic brain stem containing either developing noradrenaline (NA) cells of the locus coeruleus or 5-hydroxytryptamine (5-HT) neurons of the developing raphe system. The eyes of the recipients were sympathetically denervated. The double transplants became rapidly vascularized from the host iris. After 3 1/2 months the irides, together with their two transplants were analyzed by Falck-Hillarp fluorescent microscopy. Both the NA and the 5-HT neurons had survived and matured in the eye. Fluorescent varicose nerve terminals of the NA and 5-HT type respectively were found in all three potential receptor areas, i.e. within the CNS transplants, in the host irides and in the vas deferens transplants. In the latter, the newly formed monoamine nerve terminals arborized mainly within a well developed smooth muscle layer. The density of such new fibres was higher than or similar to that of the normally present sympathetic plexus in areas of the transplant close to the CNS transplant and lower in areas at a distance from the CNS transplant. It is concluded that immature central NA and 5-HT fibres are able to grow simultaneously into different types of sympathetically denervated smooth muscle tissues to form networks of fibres in the receptor organs resembling the normal sympathetic innervation.

Animals↗

PubMed1974